1. Field of the Invention
This invention relates to an apparatus for processing a color video signal or a color television signal.
2. Description of the Related Art
Japanese published examined patent application 6-083464 (corresponding to U.S. Pat. No. 5,038,206) discloses a picture-quality improving circuit including a chroma difference extractor. The chroma difference extractor has a cascade combination of first, second, and third equalizers. The chroma difference extractor also has first and second subtractors connected to the cascade combination of the equalizers.
In the chroma difference extractor of Japanese application 6-083464, the signal delays offered by the second and third equalizers are set smaller than the signal delay offered by the first equalizer. This setting is based on the following reason. The second and third equalizers and the second subtractor compose a device generating a signal which is used to enhance the color signal. On the other hand, the first and second equalizers and the first subtractor compose a chroma edge detector. In order to attain a high sensitivity of the chroma edge detector, the delay quantity provided by the first equalizer is set great and the signal difference is determined at points adequately distant from each other.
In the chroma difference extractor of Japanese application 6-083464, the equalizers are adjusted by an operator.
Generally, a portion of such a prior-art picture-quality improving circuit is formed as an integrated circuit chip to which an external filter block having adjustable equalizers is connected. This design allows an operator to access the filter block to adjust the equalizers. Since the filter block is not built in the integrated circuit chip, the prior-art picture-quality improving circuit tends to be large in size.